Nondestructive method for measuring the degree of cluster-induced quenching in er(3+)-doped waveguides and fibers.

Ion clustering is one of the major dissipative processes in the operation of Er(3+)-doped planar waveguide amplifiers and heavily doped fiber amplifiers. We propose and demonstrate a nondestructive method for measuring the fraction of erbium ions in doped planar waveguides and fibers that are quenched by ultrafast parasitic energy transfer in ion pairs or clusters. The method is based on unsaturable absorption measurements in the 980-nm absorption band. By combining transmission data at resonance with the corresponding data for radiation outside the absorption band, the influence of background and coupling losses can be eliminated.

Gain saturation and pump depletion in high-efficiency distributed-feedback rare-earth-doped lasers.

We propose a model for designing and analyzing rare-earth-doped distributed-feedback (DFB) lasers. The effects of pump depletion and cross-gain saturation are included and shown to be significant for high-efficiency lasers. Our simulations show good agreement with experimental data from an ytterbium-doped fiber laser. We also give some design guidelines for DFB fiber lasers.